Cannula for receiving surgical instruments

ABSTRACT

A cannula ( 10 ) receives surgical instruments ( 120 ) for performing a surgical procedure on a body ( 130 ). The cannula ( 10 ) comprises a tube structure ( 12 ) defining a passage ( 16 ) through which the surgical instruments ( 120 ) are inserted into the body ( 130 ). The tube structure ( 12 ) has a proximal end ( 20 ) and a distal end ( 62 ). The tube structure ( 12 ) includes an expandable portion ( 40 ) for enabling an increase in the cross-sectional area of the passage ( 16 ) at the distal end ( 62 ). The expandable portion ( 40 ) of the tube structure ( 12 ), when expanded, has a conical configuration.

PRIORITY INFORMATION

[0001] This application is a continuation of U.S. application Ser. No.09/772,605, filed Jan. 30, 2001, which is a continuation-in-part of U.S.application Ser. No. 09/137,335, filed Aug. 20, 1998, now U.S. Pat. No.6,187,000.

TECHNICAL FIELD

[0002] The present invention is directed to a cannula for receivingsurgical instruments for performing a surgical procedure on a body.

BACKGROUND OF THE INVENTION

[0003] Endoscopic surgical techniques allow a surgical procedure to beperformed on a patient's body through a relatively small incision in thebody and with a limited amount of body tissue disruption. Endoscopicsurgery typically utilizes a tubular structure known as a cannula whichis inserted into a small incision in the body. The cannula holds theincision open and serves as a conduit extending between the exterior ofthe body and the local area inside the body where the surgery is to beperformed.

[0004] Due to the relatively small size of the passage into the bodywhich is defined by the cannula, certain surgical procedures, such asposterior disectomies and procedures using steerable surgicalinstruments, have been difficult to perform using endoscopic techniques.

SUMMARY OF THE INVENTION

[0005] The present invention is a cannula for receiving surgicalinstruments for performing a surgical procedure on a body. The cannulacomprises a tube structure defining a passage through which the surgicalinstruments are inserted into the body. The tube structure has aproximal end and a distal end. The tube structure includes an expandableportion for enabling an increase in the cross-sectional area of thepassage at least at the distal end.

[0006] The expandable portion of the tube structure, when expanded, hasa conical configuration. The expandable portion of the tube structureincludes an arcuate slot and a guide pin disposed in the arcuate slot.The guide pin is movable from a terminal end of the slot to a secondterminal end of the slot to enable the cross-sectional area of thepassage at the distal end to increase.

[0007] The tube structure includes first and second tubular portionsattached to one another. The second tubular portion comprises theexpandable portion. The first tubular portion comprises a length ofstainless steel tubing, and the second tubular portion comprises anarcuate segment of stainless steel sheet stock rolled into a tubularshape.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The foregoing and other features of the present invention willbecomes apparent to one skilled in the art to which the presentinvention relates upon consideration of the following description of theinvention with reference to the accompanying drawings, wherein:

[0009]FIG. 1 is an exploded perspective view of a surgical cannulaconstructed in accordance with the present invention, the cannula beingshown in an expanded condition;

[0010]FIG. 2 is a perspective view of the cannula of FIG. 1 with partsremoved for clarity, the cannula being shown in a contracted condition;

[0011]FIG. 3 is a schematic end view showing the cannula of FIG. 1 inthe expanded position;

[0012]FIG. 4 is a roll out view of a part of the cannula of FIG. 1; and

[0013]FIG. 5 is a schematic sectional view of the cannula of FIG. 1during a surgical procedure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0014] The present invention is directed to a cannula for receivingsurgical instruments for performing a surgical procedure on the body ofa patient. The present invention is applicable to a variety of surgicalprocedures in which endoscopic surgical techniques are used.

[0015]FIG. 1 illustrates a cannula 10 constructed according to thepresent invention. The cannula 10 is a tubular structure 12 centered onan axis 14. The tubular structure 12 defines a passage 16 through thecannula 10. Surgical instruments are inserted into the body duringendoscopic surgery through the passage 16.

[0016] The tubular structure 12 comprises a first tubular portion 20 anda second tubular portion 40 attached to the first tubular portion. Thefirst tubular portion 20 is preferably made of a length of stainlesssteel tubing, but could alternatively be made of another suitablematerial. The first tubular portion 20 has a proximal end 22 and adistal end 24. Parallel cylindrical inner and outer surfaces 26 and 28,respectively, extend between the ends 22, 24 of the first tubularportion 20. The inner surface 26 defines a first passage portion 30 ofthe passage 16 through the cannula 10. The first passage portion 30 hasa diameter D1 which is preferably in the range from 10 mm to 20 mm.

[0017] The second tubular portion 40 of the tubular structure 12 isattached to the distal end 24 of the first tubular portion 20. Thesecond tubular portion is preferably made from stainless steel, butcould alternatively be made from another suitable material.

[0018] As best seen in the rollout view of FIG. 4, the second tubularportion 40 comprises an arcuate segment 42 of sheet stock. The arcuatesegment 42 includes first and second arcuate edges 44 and 46,respectively, and first and second planar edges 48 and 50, respectively.The first and second planar edges 48 and 50 are rolled in an overlappingmanner to form the tubular configuration of the second tubular portion40.

[0019] When the second tubular portion 40 has been rolled into itstubular configuration, the first and second arcuate edges 44 and 46define oppositely disposed first and second ends 60 and 62 (FIGS. 1 and2), respectively, of the second tubular portion. The first and secondends 60 and 62 are connected by a central portion 64. The first end 60of the second tubular portion 40 is attached to the distal end 24 of thefirst tubular portion 20 by a single fastener, such as a rivet 66. Therivet 66 extends through two aligned apertures 68 (FIG. 4) at the firstend 60 of the second tubular portion 40. The first end 60 of the secondtubular portion 40 is pivotable about the rivet 66.

[0020] The second tubular portion 40 includes parallel inner and outersurfaces 70 and 72 (FIGS. 1 and 2), respectively, extending between thefirst and second ends 60 and 62. The inner surface 70 defines a secondpassage portion 74 of the passage 16 through the cannula 10 whichextends as a continuation of the first passage portion 30 in the firsttubular portion 20.

[0021] An arcuate slot 80 is formed in the second tubular portion 40 andextends between the inner and outer surfaces 70 and 72 of the secondtubular portion. The arcuate slot 80 extends along a curvilinear path inthe central portion 64 of the second tubular portion 40 toward thesecond end 60 of the second tubular portion. The arcuate slot 80 has afirst terminal end 82 located in the central portion 64 of the secondtubular portion 40. A second terminal end 84 of the arcuate slot 80 islocated adjacent the intersection of the second arcuate edge 46 and thefirst planar edge 48 of the arcuate segment 42.

[0022] A guide pin 90 is attached to the inner surface 70 of the secondtubular portion 40 adjacent the intersection of the second arcuate edge46 and the second planar edge 50. In the tubular configuration of thesecond tubular portion 40, the guide pin 90 is located in the arcuateslot 80 and is movable along the curvilinear path of the arcuate slot. Awasher 92 is secured an inner end of the guide pin 90 to retain theguide pin in the arcuate slot 80.

[0023] The second tubular portion 40 of the tubular structure 12 isexpandable from a contracted condition shown in FIG. 2 to an expandedcondition shown in FIG. 1. In the contracted condition, the guide pin 90is located in the first terminal end 82 of the arcuate slot 80 in thesecond tubular portion 40 and the second passage portion 74 defined bythe second tubular portion is cylindrical in shape. The second passage74 has a generally constant diameter D2 (FIGS. 2 and 3) which isapproximately equal to the diameter D1 of the first tubular portion 20.Thus, the cross-sectional area of the second passage portion 74 at thesecond end 62 of the second tubular portion 40, which is function of thediameter D2, is approximately the same as the cross-sectional area atthe first end 60 of the second tubular portion and is approximately thesame as the cross-sectional area of the first passage portion 30 in thefirst tubular portion 20.

[0024] In the expanded condition, the guide pin 90 is located in thesecond terminal end 84 of the arcuate slot 80 in the second tubularportion 40 and the second tubular portion has a conical configuration.At the second end 62 of the second tubular portion 40, the secondpassage portion 74 has a diameter D3 (FIG. 3) which is larger then thediameter D2 of the second passage portion at the first end 60.Preferably, the diameter D3 of the second passage portion 74 at thesecond end 62 of the second tubular portion is 40% to 80% greater thanthe diameter D1 of the second passage portion at the first end 60. Thus,in the expanded condition, the cross-sectional area of the secondpassage portion 74 at the second end 62 of the second tubular portion40, which is function of the diameter D3, is 40% to 80% greater than thecross-sectional area of the second passage portion at the first end 60of the second tubular portion.

[0025] The cannula 10 includes an outer layer 100 (FIG. 1) formaintaining the second tubular portion 40 of the cannula in thecontracted condition. It is contemplated that other suitable means formaintaining the second tubular portion 40 in the contracted conditioncould be employed. In accordance with a preferred embodiment of thepresent invention, the outer layer 100 comprises a section of plastictubing 102 which is heat shrunk over both the first and second tubularportions 20 and 40 to hold the second tubular portion in the contractedcondition.

[0026] In addition, a loop of nylon string 104 for tearing the heatshrunk tubing 102 is wrapped around the heat shrunk tubing so that itextends both underneath and on top of the tubing. An outer end 106 ofthe string 104 extends beyond the tubing 102.

[0027] The cannula 10 further includes an actuatable device 110 forexpanding the second tubular portion 40 from the contracted condition tothe expanded condition. In accordance with a preferred embodiment of thepresent invention, the actuatable device 110 comprises a manuallyoperated expansion tool 112. The expansion tool 112 resembles a commonpair of scissors and has a pair of legs 114 pivotally connected to oneanother. The expansion tool 112 includes a frustoconical end section 116formed by a pair of frustoconical halves 118. Each of the frustoconicalhalves 118 extends from a respective one of the legs 114 of theexpansion tool 112. It is contemplated that other suitable means forexpanding the second tubular portion 40 toward the expanded conditioncould be employed, such as an inflatable balloon (not shown).

[0028] During an endoscopic surgical procedure, the cannula 10 isinserted into the body of a patient in the contracted condition. Theouter end 106 of the string 104 is then manually pulled on by thesurgeon. Pulling on the string 104 tears the heat shrunk tubing 102which is then removed from the cannula 10 by the surgeon. With the heatshrink tubing 102 removed, the second tubular portion 40 of the cannula10 is thereby released for expansion toward the expanded condition.

[0029] Next, the expansion tool 112 is inserted into the passage 16 inthe cannula 10 until the frustoconical end section 114 is located at thesecond end 62 of the second tubular portion 40. The legs 114 of theexpansion tool 112 are manually separated, causing the frustoconicalhalves 118 to separate also. As the halves 118 separate, a radiallyoutward directed force is exerted on the inner surface 70 of the secondtubular portion 40 by the halves 118, causing the second tubular portionto expand toward the expanded condition. Under the force of theexpanding expansion tool 112, the guide pin 90 slides from the firstterminal end 82 of the arcuate slot 80 to the second terminal end 84 ofthe arcuate slot to permit the expansion of the second tubular portion40. The expansion tool 112 can be rotated about the axis 14 to ensurethat the second tubular portion 40 of the cannula 10 is completelyexpanded to the expanded condition. The expansion tool 112 is thencollapsed and removed so that one or more surgical instruments(indicated schematically at 120 in FIG. 5) can be received through thecannula 10 and inserted into a patient's body 130.

[0030] The expandable second tubular portion 40 of the cannula 10provides a significantly larger working area for the surgeon inside thebody 130 within the confines of the cannula. As a result, thesimultaneous use of a number of endoscopic surgical instruments,including but not limited to steerable instruments, shavers, dissectors,scissors, forceps, retractors, dilators, and video cameras, is madepossible by the expandable cannula 10.

[0031] It is contemplated that the cannula 10 described herein could bethe centerpiece of a endoscopic surgical kit which would include anassortment of surgical instruments designed and/or selected for use withthe cannula.

[0032] From the above description of the invention, those skilled in theart will perceive improvements, changes and modifications. Suchimprovements, changes and modifications within the skill of the art areintended to be covered by the appended claims.

What is claimed is:
 1. A system for providing minimally invasive accessto the spine of a patient, said system comprising: an elongate bodyhaving a distal end, a proximal end, an outer surface and an innersurface, said inner surface defining a passage extending through theelongate body through which instruments can be inserted to the surgicallocation; and an expander configured to be inserted into the passage andto engage the inner surface to cause opposing portions of the distal endof the elongate body to be moved transversely to increase access to thesurgical location.
 2. The system of claim 1, wherein the expander isconfigured to engage the inner surface to move the elongate body suchthat the cross-sectional area of the passage at a first location isgreater than the cross-sectional area of said passage at a secondlocation, wherein the first location is distal to the second location.3. The system of claim 2, wherein the elongate body comprises rigidmaterial extending around substantially the entire perimeter of thecross-sectional area between the first and second locations.
 4. Thesystem of claim 1, wherein the inner surface defining the passage ismade of a smooth metal.
 5. The system of claim 1, wherein the passage issized to receive at least two instruments simultaneously.
 6. The systemof claim 1, wherein the expander comprises a pair of legs pivotallyconnected to one another.
 7. The system of claim 1, wherein the elongatebody includes an area overlap between the inner surface and outersurface, and wherein actuating the expander reduces the area of overlap.8. The system of claim 1, wherein the elongate body includes twoportions capable of pivoting relative to each other, and whereinactuating the expander causes the two portions to pivot relative to eachother.